Regenerative telegraph repeater



March 5, 1935;

O. H. DAVIDMEYER Er AL REGENERATIVE TELEGRAPH REPEATER LOOP EAST Filed April 20. 19:53

ERR

LOOP WES T A B C 0. H. IDA V/DSMEYER A.H.S7OL7'ENBERG INVENTO/PS A TTORNE I" Patented Mar. 5, 1935 Y UNITED STATES REGENERATIVE TELEGRAPH'REPEATER omue H. Davidsmeyer and Arthur H. Stoltenberg, Chicago, 111;, assignors to American Telephone and Telegraph Company, a corporation of New York Application April 20,1933, Serial No. 667,088

6 Claims.

This invention relates to regenerative telegraph repeaters, and particularlyto telegraph repeaters of the start-stop type.

An object of the invention is to regenerate into substantially their original formsignals which have become distorted in transmission, so that they may be subjected to distortion due to subietquent transmission without loosing their iden- A further object of the invention is to simplify the operation and maintenance of regenerative repeaters of this type.

The invention is in the nature of an improvement on the regenerative telegraph repeater disclosed in Patent No. 1,771,453, issued to G. S. Vernam on July 29, 1930. In accordance with that disclosure the telegraph. repeater is provided with a start-stop distributor for each direction of transmission; each distributor has a set of retransmitting contacts for transferring impulses from the receiving relay to the retransmitting relay and a set of locking contacts for locking of the receiving relay by means of its biasing winding during the greater part of each received impulse.

In accordance with the present invention, a rotary distributor is provided with a single set of interrupter contacts, whereby contact trouble is reduced.

The transmitting and locking circuits are combined in such a manner that they may be controlled by only a single set of distributor contacts, and more particularly the receiving relay is provided with a locking winding, separate from its biasing winding, which is serially included with the operating winding of the retransmitting relay in a single operating circuit controlled by the contacts of the receiving relay and timed by the single set of interrupter contacts of the distributor.

General description of apparatus A regenerative repeater system in accordance with this invention for repeating signals in either direction between two line sections, one of which for convenience, is called loop east and the other loop west, is illustrated in Figure 1 of the draw- In Fig. 2 is shown diagrammatically an examthrough a source of current.

released by start magnet 16, the brush arm being 0 driven through a friction clutch in a well known manner. Associated with each distributor are a locking relay, a retransmitting or sending relay, and a receiving relay, the relays associated with theloop wes'tbeing identified as WLR, WSR and WRR, respectively, and those with the loop east ELR, ESR and ERR, respectively. The function of these relays will be made clear by the following detailed description of the operation of the system in repeating signals from the loop 3 west into the loopeast.

: Detailed description of operation In systems of the type described the line cir-- cuit, or loop as it is termed, is normally closed Thus, referring to the drawing, the loop west is. normally closed through a source of current at the distant end, the lower or operating winding of the west receiving relay WRR and the armature and contact of the west sending relay WSR. For the purpose of explanation it is assumed that an electron flow from left to right through any relay winding, as it is shown in the drawing, urges the relay armature from left to right, and vice versa when the electron flow is in the opposite direction. The direction of the electron flow fromthe source at the distant end of the loop west is always from left to right through the relay WRR,

as indicated by the arrow. Thus the armature 40 of this relay is held on its marking contact by a loop current, which may conveniently be made approximately 60 milliamperes. An opposing current of approximately 30 milliamperes flows through the middlewinding, which will hereinafter be termed the biasing winding. The circuit for the 30 milliampere current extends from negativebattery over the contact and armature oi the west locking relay WLR through resistance 11, the parallel upper windings of the west I locking relay WLR and the west sending relay WSR,'which are shunted by a resistance 12, and through the middle or-biasing winding of the west receiving relay to ground. This locking current of 30 milliamperes holds the west locking and sending relays on their marking contacts and tends to move the receiving relay armature to its spacing contact. The effective current in the winding of the locking and sending relays is small compared with that in the middle winding of the receiving relay because of the shunting effect or resistance 12.

When all the relays are in their idle condition (on their marking contacts)" the start magnet circiut for the west to east distributor is short-v circuited. This circuit extends through the stop position of the distributor a's'follows': from neg ative battery through the marking contact, armature and locking winding of the west receiving relay WRR, over the common ring 18, brush SB, stop segment SS of the distributor, through the start magnet 16 and back to negative battery over the armature and marking contact of-the east locking relay ELR.

Repeating signals from west to east In start-stop telegraph systems. seven impulses are usually transmitted for each signal character. These comprise an initial or starting impulse, which is commonly a spacing impulse, followed by five impulses which may be either marking or spacing and represent the signal character to be transmitted. These are followed by a last or stop impulse which is a marking impulse and stops the d1stributor; it is'termedl the stop impule. For purposes of explanation it will be assumed that an F signal is to be repeated from the loop west into the loop east. The seven impulses of an F signal are the start, which is spacing, No. l marking, No. 2 spacing, No. 3 and No. 4 marking, No. 5 spacing and the stop impulse, which is marking. Such'a series of impulses is graphically represented in Fig. 2, the

marking impulses being represented by values above the zero line and the spacing impulses as zero values of current. Thusrthe loop is normally closed, but changes to open or spacing condition at time A, at'which the start impulse is received.

This start or open impulse removes the 60 milliampere current from the operating winding of the west receiving relay WRR and permits the 30 milliampere biasing current in the middle winding to move This applies positive battery to one end. of the start magnet circuit and current flows from positive battery at the spacing contact of the west receiving relay WRR throughthe contact, armature and locking winding of the relay, Over the common ring 18, brush SB and stop segment SS of the distributor, through the start magnet 16' to negative battery at the marking contact of the east locking relay ELR. Start. magnet 16 thereupon operates to raise the stop latch 17 and release the brush arm carrying the'brush SB. The upper or looking winding ofrelay WRR receives current in either position of the armature in such a direction that it will exert a looking force upon the armature, which consequently will be aiding the force by which the'armature was operated. tailed and the by a reverse force until deenergized. i I

Almost immediately after leaving the stop segment, the brush SB contacts with sending 'seg' ment No. '1, which'applies positive battery from the spacing contact and through the locking winding of relay WRR, over the common ring 18, brush SB, and segment No. 7,-through'resistance armature isheld against operation the locking windingis the armature to the spacing contact;

Contact chatter is thereby cur- 22 and the upper or operating windings of the east locking relay ELR and the east sending relay ESE. to ground. An electron flow from right to left therefore occurs through the upper windings of these two relays, overcomes the weak locking current through the lower windings, moves their armature to their spacing contacts and opens the loop east at the east sending relay contacts, thereby retransmitting the start impulse over the loop east. These relays are now locked on their spacing contacts by current from positive battery over the armature of the east locking relay ELR, through resistance 25, the parallel locking windings of the relays ELR and ESR, which are shunted by a resistance 26, and through the biasing winding of the east receiving relay ERR to ground. As in the case of the west locking and sending relays, resistance 26 may have such a value as to limit the current in the lower windingsof relays ELR and ESR to about 11 milliamperes. It may be noted at this point that the current in the middle or biasing winding of the east receiving relay ERR is now in such a direction as to hold the armature on the marking contact while the loop east is open at the contacts or" the east sending relay. At this time the start magnet is deenergized, since its circuit has been opened. by the brush SB passing ofi .the stop segment SS. The locking winding of relay WRR, however, remains efiective in holding the armature to spacing as long as the brush SB is passing over segment No. '7, and by adjustment of this locking current to about 60 milliamperes the combined force of the locking winding and the biasing winding is suflicient to overpower the force of the operating winding should a 60 milliampere marking impulse arrive over loop west, while the brush is passing over segment No. 7; this provision thus insures the completion of the operation and the locking of relays ELR, ESR and ERR just described. Thus a premature change in the west loop of the condition which brought about these operations will not interfere with their completion. However, as soon as brush SB leaves the segment No. 7, the locking becomes ineffective and the relay is free to respond to a new impulse while the brush SB passes from segment No. 7 to segment No. l.

, The brush traverses the segments in the off-stop positions in approximate synchronism with the signal impulses from the loop west, so that by the time the brush SB reaches the No. 1 segment the first impulse of the F signal (which is a marking pulse as shown'in Fig. 2) will have been received by the West receiving relay, the armature of which now will be on its marking contact.

7 Brush SB contacting with segment No. 1 completes a circuit through the locking winding of the west receiving relay WRR, over common ring 18, brush SB and segment No. 1 of the distributor, through resistance 22 and the operating windings of the east locking relay ELR and east sending relay ESR. to ground, which causes the armatures of relays ELR. and ESR to move to their marking postitions; and a marking impulse is sent into the loop east. It will be seen that an impulse of the correct polarity necessarily must be sent from the west receiving relay WRR, through the east locking and sending relays ELR and ESR, because the receiving relay armature is again locked on its contact during the time the brush SB is contacting with sending segment No. l by a 60 milliampere' current flowing through the locking winding in a direction to oppose and overcome the 30 milliampere current in the biasing winding.

contact of the West locking relay WLR,-and op.- erates the start niagneton the east to west distributor in the same manneras described in detail above for the west to east distributor. The

east to west distributor brush then moves-over.

its associated segments and, since the loop east remains open, transfers only spacing. impulses to the west sending relay, WSR'andwesttlocking relay WLR which 'operateand hold their armatures in spacingposition, thereby keeping the loop west open and biasing relay WRR to marking, sothat relays WSR and \WLRwill .operate to marking, lock and-keep the loop east closed. After completing one revolution the east to west istributorbrush stops, because both sides 'of the start magnet are: connected to positive battery, at the spacing contacts of relays WLR and ERR, respectively. When the west operator observes that' the loop west-has been opened, he knows'that the east operator wishes to transmit to him and he closes the loopwest through his reciving apparatus. Transmission of signals from the loop east to the loop-west through the east to west distributor can then take place in thesame manner'as described in detail above in connection with transmission through the west to east distributor. I J v Summary i The functions of'the different 'elementsof the system may be briefly set forth as follows:

Each receiving'relay responds to line signals received from its associated lcop and repeats them through the sending segments of the associated distributor to the sending relay in the opposite loop. I r

The function of the sending relays is selfevident. f

Each locking relay'moves in unison with the associated sending relayand supplies current of the requisite polarity to'lock the sending relay firmly on one contact or-tlie other, when the operating winding of the sending relayis not energized. It also controls. 'the polarity of the potential applied to one end of the start magnet circuit andthusprevents the brusharm from revolving continuouslyduring a break or open signal. A third function is to control the polarity of the biasing current in the receiving relay to hold the armature against its marking contact when a spacing signalis transmitted from the corresponding sending relay;

The function of each distributor is to furnish in its stop position a path for the start impulse from the-armature of the associated receiving relay to the start magnet; and-thereafter, during the transferring gof signals, to temporarily lock the receivingrelay at the center; of each received signal impulse to prevent distortion inth'e incoming signals from being. retransmitted." A second function is to permit the associated receiving relay to control the opposite sending relay only while the receiving relay is locked in position by i the distributor, and to limit this control timeto be only suficient'fo'r the certain locking of the opposite sending relay in its new position, thus reducing the looking tim'eflforthe receiving relay many and varied" types," the principal requirements of such a device being asetof off-normal contacts closed inthe stop position and a set of interrupter contacts operated in, off-stop posi: tions by a-motor driven member in its travel from one stop position tothe next upon the releaseof the member inzresponse to the start, impulse.

Thus the start-stop interrupter disclosed by M.'P.'

resistances partly in multipleand partly inseries relation to the start. magnet, eifective inaccordance with :known principles in overcoming the retarding effects ofthe inductance associated with the: start circuit and thusjinsuring a quick start of thedistributor; similar; networks may also be inserted .for the reduction of sparks at relay and distributor contacts without departing from the spirit of the. invention. 7 v V The inventionfurthermore is notilimited to regenerative repeaters; for use in start-stopsystems employingthe '7 unitcode, but is readily adapted to any; other uniform start-stop code.

What is claimed is.v 7 1. A regenerative telegraph repeater comprising receiving relay means havingcontacts and a locking-winding for self-locking over said contacts, retransmitting relay means having an operating winding connected to said contacts for transfer of impulses from said receiving relay means, and start-stop timingmeans connected in circuit with the contacts of saidreceiving relay means and having a single set ofinterrupter con tacts for simultaneous control ofsaid locking winding and said operating winding.

2. A regenerative impulse repeater comprising receiving relaymeans, sending relay means, a

single set of interrupter contacts motor driven in synchronism "with incoming impulses, a transfer circuit for operation of said sending-relay means by said receiving relay means and intersignal repeater means, circuit means for the transfer of impulses from said receiving relay means to said sending relay means, ;a'single1set of ,interrupter contacts for controlling the period of transfer by said cir cuit means of eachimpulse,-a winding included in said receiving relay means. for the locking thereof over said circuit means during the periods of impulsetransfer and a winding included in said sending realy means; for the self-locking thereof" between the periods of impulse transfer. 7 4. A regenerative telegraph signal repeater in accordance with'claim 3, in which said winding for the lockingof said receiving relay means is serially included in said circuit means to be traversed ,by the transferred impulses.

5. Astart-stop regenerative telegraph repeater comprising receiving relay-means including a locking; winding and contacts, distributor mech anism having: a single set of circuit interrupting contacts fortiming lof relay; operations in iso- The neiit impulse of the .F signal, the No. 2 impulse, is an open or' spacing impulse. Since the locking circuit for relay WRR is opened when the brush SB leaves segment No. 1, the relay will presently be underthe control of the normal biasing current flowing from negative battery at the marking contact of the west locking relay WLR, through resistance 11 and the upper windings of the relays WLR and WSR'and theresistance 12 in parallel. 'I'here being no current in the line winding of relay WRR at this time, the armature is moved to its spacing contact by the normal 30 milliampere current from the above source through its biasing winding. The east locking and sending relays ELR and ESR remain on their marking contacts, however, since they are being held bythe 11 milliampere current'in their locking windings, their operating windings being opened at this time at the segments of the distributor. When'the brush SB contacts with the No. 2 segment, it once again completes the locking circuit from the armature of the west receiving relay WRR through its locking winding. In the same way as was previously described, the sending brush SB in passing over the segment No. 2 causes the-operation of the relays ELR and ESR to their spacing contacts and their locking in that position to transmit a spacing signal out over the loop east, and also causes the reversal of the current in the biasing winding on relay ERR to hold this relay in its marking position during the opening 01' the loop east. I

It has'been assumed heretofore that the impulses were received undistorted, or substantially as they were transmitted, as shown in Fig. 2. It will now be assumed for purposes of illustration that the No. 3 and No. 4 impulses are distorted when they are received-over the loop'west. For instance, referring to Fig. 3 assume that nearly 50% of the first part of the No. 3 impulse has been wiped out and that nearly 50% of the latter part of the No. 4 impulse has also been eliminated, possibly by some fortuitous interference on the lines. Thus, instead of a marking impulse extending from timeD to time F, as shown in Fig. 2, there will be a much shorter marking impulse, as shown in Fig. 3, which begins a little earlier than half way between times D and E and ends only a little later than half Way between times E and F. It is noted here that the distributor face is oriented with respect to the incoming signals, so that the brush SB just contacts with the edge of a segment when the exact center of an undistorted incoming impulse is being received. Thus the front edge of the No. 1 segment is on a line with the center of the impulse received between times B and C. -Therefore, the west receiving relay armature will be moved to'its marking contact by the incoming distorted No. 3 impulse just before the brush contacts with the No. 3 segment, and immediately upon reaching this segment the locking circuit through the upper winding of relay WRR is closed simultaneously with'the operating circuit for relays ELR and ESR, so that the No. 3 impulse will be correctly repeated into the loop east. a 7

1e No. 4 impulse (which is also marking as shown in Fig. 2) a is next received in the operating winding of the receiving relay WRR. As stated above, it is being assumed that/nearly 50% of the latter part of the No. 4 impulse has been cut off by distortion, as shown in Fig. 3, but the brush SB makes contact with the No. 4- segment just before the current in the loop west goes to zero.- The west recivingrelay armature, therefore, remains locked on its marking contact in spite of the distortion, since the locking circuit through the upper winding of the receiving relay WRR is completed by the brush closing on segment No. 4 just before the receiving relay armature would have moved from its marking contact. Therefore, current of the correct polarity is necessarily applied to the operating windings of the east locking and sending relays ELR and ESR when the brush SB makes contact with No. 4 sending segment. Because the locking time for relay WRR is equal to the time in which the brush passesthe segment and is made sufiicient, by the proper width of the segment, to fully insure operation of relays ELR and ESR, a premature change in the current in loop west, due to distortion, will not interfere with the proper operation of relays ELR and ESR, as long as the distortion is less than 50%. Also, since relays ELR and ESR lock in their operated position before the brush leaves the segment, relay WRR is left free to respond to the next impulse as soon as the brush goes oil the segment.

The No. 5 and No. 6 impulses are assumed to be perfect signals and they will be repeated in a normal way, as were the No. 1 and N0. 2 impulses. I

TheNo. 6 impulse is always a marking impulse and is used to stop the brush and set the relays in their normal position in preparation for the repeating of the next signal. The armature of the west receiving relay WRR is moved to its marking contact and the brush thus connects marking current to the operating windings of the east locking and sending relays, thereby closing the loop east and connecting negative battery to the start magnet 16 at the armature and marking contact of the east locking relay ELR. The other end of the start magnet circuit will also be connected to negative battery at the marking contact of the west receiving relay WRR when finally the brush SB contacts with the stop segment SS of the distributor. The magnet, therefore, will not operate until the next start impulse arrives over loop west.

Reversing direction of transmission 1 Heretofore it has been assumed that the loop east was closed at the distant station through a source of current applying about 60 milliamperes through the loop to the upper or operating winding of the east receiving relay ERR. This is the normal condition at, the distant station while it is receiving. If, while receiving, the distant. operatorshould wish to signal the sending station, he would open the loop east for a short interval. Opening of the loop east deenergizes the upper winding of the east receiving relay ERR, leaving the relay under the control of its biasing winding. When, during the continued arrival of signals over the loop west, a marking impulse places relays ELR in marking position, the normal biasing current of 30 milliamperes from the marking contact of the east locking relay ELR, through resistance 25, the lower windings of relays ELR and ESR and resistance 26 in parallel, and the biasing winding of relay ERR to ground moves the armature of relay ERR. to its spacing contact. This completes a circuit from positive battery over the spacing contact and armature and through the locking winding of the east receiving relay ERR, over the common ring, brush, stop segment and start magnet of the east to wcstdistributor to negative battery at the armature and marking chronism with received impulses and having a start magnet and a stop position, a start circuit for said magnet extending in said stop position to contacts on said receiving relay means, retransmitting relay means including contacts and winding for self-locking between impulses from said receiving relay means, and circuit means connected from contacts on said receiving relay means and through the locking winding of said receiving relay means and intermittently completed through said set of contacts for simultaneous transfer of impulses to said retransmitting relay means and self-locking of said receiving relay means.

6. A start-stop regenerative telegraph repeater connected between a west line circuit and an east line circuit, including east-west equipment for retransmission from said east line to said west line and a corresponding West-east equipment; said east-west equipment comprising receiving relay means having an operating winding in said east line, biasing winding, separate locking winding and contacts; sending relay means having contacts in said west line, locking'winding and contacts for self-locking between operations; distributing mechanism for timing of relay operations in isochronism with received signal impulses and having a single set of circuit interrupting contacts, a start magnet and a stop position; a start circuit controlled by said receiving relay means for operation of said magnet in stop position only; an operating circuit for said sending relay means intermittently completed through said set of contacts in off-stop positions only for transfer of impulses from said receiving relay means; a locking circuit for the lockingwinding of said rece1ving relay means intermittently completed through said set, of contacts for self-locking thereof in off-stop positions during transfer of individual impulses; and a holding circuit from the locking contacts of the sending relay means in said west-east equipment for the biasing Winding of said east-west receiving relay means in said stop position during transmission through said west-east equipment.

ORVILLE H. DAVIDSMEYER. ARTHUR H. STOLTENBERG. 

